Hi I have a problem with my fry they are around a week or so old now. But some of the fry seem to be bigger than others and some are not swimming right and are very thin. Also seem that some of the fry are that fat that they can't swim to the top of the tank without sinking. I feed them banana worm and I have change the water every day my heater at around 82. can anyone help please

Its not uncommon for fry to be different sizes-an hour or so difference in age can be a big difference in the fish world......

What size is the tank, how much are the daily water changes, is the tank full to the top and do you have plastic wrap over it to help retain heat and humidity..... how many times fed per day and banana worms the only food-have you seen the fry eat the worms...

Usually you can find starter cultures of most of the cultures used on aquabid.....you can also use/culture/feed- microworms, BBS, vinegar eels, white worms and a few others....live is best to feed for at least the first 2-3 weeks from free swimming stage...

The tank is around a 25L I think but I have a bigger one waiting for them when there a bit bigger. I have around 40 to 50 fry. I have a glass top on so I don't think it's the heat. I change around 1L of water a day do I need to change more? I been trying to up the water every day. It was at around 5 inches and now it's around 8 inches deep.yes they are eating the banana worms I also have microworms. I feed them twice a day one in the morning and one at night. But i have only feeding them once a day since I been having problem with some of the fry. When I change the water I put in stress Zyme because it says it help keep the tank clean as well as tap water conditioner is this the problem do I need to put this in? Or am I feeding them to much?

Okay...it about 6.6gal-glass cover with about 40-50 week old fry, 82F temp, 8in water with 1L/0.3gal water change per day with increase of water level from 5in to now 8in-adding more like temp dechlorinated water than being removed (good) and you are having some fry issues-some look thin-some look fat with some buoyancy and/or swimming issues-all somewhat lethargic....

I should have asked this-but....any live plants, if so, how many what species...a pic of the fry tank would help, is this your first spawn or fry rearing attempt.....bare bottom or if substrate what kind, any common snails or other livestock in the fry tank like shrimp-is the male removed, how long after hatch did they start to free swim-when did you first add food....

While its not uncommon to have some deaths and/or sickly looking fry especially for the first two weeks-you should have some healthy thriving fry if the system is healthy to start......

IMO/E-the skinny lethargic fry should be culled, increase water changes to 1gal removed with 1.5gal added using like temp dechlorinated water by drip/gravity over 20-30min
Once the tank is full-start making 50% daily water changes-with gravity refill over 20-30min
The glass cover should have water condensation on it-if not-use plastic veggie wrap over the top-it is important for the air above the water to be warm and humid for the labyrinth organ and that is gong to be developing soon-usually starting in the 2 weeks range up to 5 weeks

I have never fed banana worms and don't know that much about them as far as size, nutrition.....
But with microworms-offer small amounts 3 times a day and observe them eating-watch their tummies for fullness-they should look round

If you have live plants add more to the water column to give them a place to rest near the top and if you have any common snails add a few to help create infusoria for the small fry to feed on, to help clean up uneaten food to prevent decay and fouling the water and to eat any dead fry before they can decay.

I think I took the male out to soon around a day to soon I no this now but at the time I didn't get what they ment by free swimming I just thought if one of the fry was to swim straight then I should take the male out so I did. This is my second attemp first time I put in salt because I read that it would help the male to build a bubble nest. He did make one but all the fry died within a couple of days that was around 6 month ago and I been doing my homework to be a better breeder. I not seen a lot of the fry dead only around 2 or 3. I got banana worm because it says that its smaller than micro worm and is good for first feed they have been eating it. My first feed was when I took the male out. I don't have and gravel or any live plants in the tank only a couple of plastic ones. I don't have any other fish in the fry tank. I do have some apple snails in my other tank tho but they make a lot of mess at the bottom of the tank and I didn't want the snails to eat any of the fry so I took them out. Also been having problems with keeping the bottom of the tank clean I was using leaves to darken the water to help my male breed because I read up that it will help with that I can't remember what the leaves are called tho. They did work but left dirt at the bottom of the tank that I can't get up because all the fry are at the bottom of the tank.

The leaf dirt is fine-I wouldn't worry too much about it...hard to imagine worms smaller than microworms....lol...but that is good to know.....

You can remove the male at any point-sometimes we have to remove him early especially if he is an egg/fry eater...so I think you are fine on that....

Usually snails will not harm healthy fry-but they will eat dead/dieing fry and that is what you want them to do....the poop snails produce is safer for the fry than the decay of food/fry-different bacteria are produced.

If you have more fake plants-add them-this will at least give them a place to rest off the bottom of the tank...

If you still have salt in the tank-I would start getting it out and not replace it-not good for the fry....